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ARS Home » Plains Area » Grand Forks, North Dakota » Grand Forks Human Nutrition Research Center » Healthy Body Weight Research » Research » Publications at this Location » Publication #79528
Title: ZINC ABSORPTION, MINERAL BALANCE AND BLOOD LIPIDS IN WOMEN CONSUMING CONTROLLED LACTO-OVO-VEGETARIAN VS OMNIVOROUS DIETS FOR EIGHT WEEKS

Author
item Hunt, Janet
item MATTHYS, LORI - UNIV OF NORTH DAKOTA
item JOHNSON, LUANN - UNIV OF NORTH DAKOTA

Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: There is concern about the adequacy of zinc intake from vegetarian diets because meat, poultry and fish are excellent sources of zinc, and because high consumption of whole grains and legumes, sources of phytic acid, may impair the absorption of zinc. Zinc absorption and plasma zinc were studied in 21 premenopausal women who consumed a lacto-ovo-vegetarian diet t and a nonvegetarian diet for 8 weeks each. Both diets were provided in controlled, weighed amounts by the research center. The lacto-ovo-vegetarian diet contained no meat, poultry, or fish, but dairy and egg products, and plenty of legumes and whole grain breads and cereals. Plasma total cholesterol and the various ("good" and "bad") types of cholesterol were reduced 7-12% on the lacto-ovo-vegetarian diet. Blood pressure was unaffected. The lacto-ovo-vegetarian diet resulted in a 21% reduction in the efficiency of zinc absorption, which together with a 14% reduction in dietary zinc content, reduced the amount of zinc absorbed from the lacto-ovo-vegetarian diet by 35%. Plasma zinc was reduced by 5%, within the normal range. There was no net body loss of zinc: zinc intake was greater than zinc excretion on both diets. The results suggest that while there is a greater risk of zinc deficiency in persons consuming lacto-ovo-vegetarian, compared with omnivorous diets, zinc requirements can be met on such a diet. The results will help nutritionists advising persons on vegetarian diets. Information on zinc bioavailability from common diets can contribute to establishing recommended dietary zinc intakes.

Technical Abstract: Zinc absorption, mineral balance, and blood lipids were measured in women consuming controlled lacto-ovo-vegetarian and nonvegetarian diets. Twenty- women, age 33 +/- 7 (20 to 42) y, consumed both diets for 8 wk each in a cross-over design. The lacto-ovo-vegetarian and nonvegetarian diets provided, respectively, (by analysis) 970 and 952 mg calcium, 1.8 and 1.3 mg copper, 367 and 260 mg magnesium, 5.9 and 2.5 mg manganese, 1457 and 1667 mg phosphorus, 9.1 and 11.1 mg Zn, and (by calculation) 40 and 16 g dietary fiber, 2.5 and 0.8 mmol phytic acid, phytate: Zn molar ratios of 14 and 5, and phytate X Ca: Zn millimolar ratios of 344 and 111. Dietary zinc absorption was measured by extrinsic isotopic labeling and whole body counting. Plasma cholesterol, cholesterol fractions, and lipoproteins were reduced 7-12% on the lacto-ovo-vegetarian diet. Blood pressure was unaffected. Calcium, copper, magnesium, and phosphorus balances were similar between both diets; manganese balance tended to be greater (p<0.07) on the lacto-ovo-vegetarian diet. The lacto-ovo-vegetarian diet was associated with a 21% reduction in absorptive efficiency which, together with a 14% reduction in dietary zinc content, reduced the amount of zinc absorbed by 35%, (2.4 vs. 3.7 mg/d) and reduced plasma zinc by 5% within the normal range. Zinc balance was maintained on both diets. The results suggest that while there is a greater risk of zinc deficiency in persons consuming lacto-ovo-vegetarian, compared with omnivorous diets, with inclusion of whole grains and legumes zinc requirements can be met and zinc balance maintained on such a diet.